Sediment container and cap and analysis technique



Dec. 2, 1969 R. K. BERNSTEIN ETAL 3,481,712

SEDIMENT CONTAINER AND CAP AND ANALYSIS TECHNIQUE Filed Feb. 7, 1966 2 Sheets-Sheet l W 5 MM M B, N m? V60 7 N3 7 PM J Dec. 2, 1969 R. K. BERNSTEIN ET AL SEDIMENT CONTAINER AND CAP AND ANALYSIS TECHNIQUE 2 Sheets-Sheet 2 Filed Feb.

United States Patent US. Cl. 23-292 6 Claims ABSTRACT OF THE DISCLOSURE A capped sediment container for initially containing sediment laden liquid and for use with a centrifuge adapted to fractionate the liquid and separate the sediment therefrom. The combination includes a substantially hollow sediment container having an open end and a closed end defining a reservoir for receiving the sediment collected during centrifugation of the liquid. The reservoir is so constructed and arranged as to retain a predetermined quantity of the liquid therein by surface tension and atmospheric pressure. A cap is mounted on the open end and the cap and the container define connecting means to connect the cap with the container and seal the liquid therein. The method of use of said cap container to fractionate a liquid is also defined herein.

This invention relates to an improved centrifugation container and cap therefor as well as a procedure for analyzing the solid phase of liquid suspensions such as urine.

According to accepted and somewhat standardized procedure for preparing and examining urinary sediment, a predetermined volume of a specimen, ordinarily to mls., is poured into a test tube. This tube is centrifuged until the sediment is concentrated at the bottom. Following centrifugation, the supernatant material is decanted, aspirated or pipetted or otherwise poured oif. The minute amount of solid sediment is allowed to remain together with anywhere from one drop to one ml. of residual supernatant. Under the circumstances, the amount of supernatant left at the bottom of the tube is not readily controlled by the operator; and some operators may remove all of the supernatant and then pipette a measured amount of the supernatant back into the test tube. At this time, the sediment is thoroughly suspended in the supernatant by either corking the test tube and shaking it, or by flicking the bottom of the test tube with the finger, or by stirring the sediment with a pipette or stirring rod. A small amount of the suspended sediment is drawn up into a pipette and one drop is deposited on a microscope slide. The remaining sediment is retained in the test tube until after microscopic examination of the first drop. A cover glass may be placed over the drop of sediment on the slide before the preparation is examined under the microscope. At some laboratories, a small amount of stain may be added to the sediment remaining in the test tube to facilitate the examination process. If there is any concern over the adequacy of the drop being examined, the sediment in the test tube is resuspended and another drop is placed on a fresh slide for examination. The microscope slide and cover glass are usually discarded together with any disposable pipettes employed while the glass test tube and other reusable items are washed and cleaned between tests. Thus, the large number of steps required to be performed and the difliculty of maintaining control as to the quantity and uniformity of suspended sediment from test to test will be readily evident.

It is, therefore, a principal object of this invention to provide improved techniques for the analysis and examination of sediment of liquid such as urine.

Another object is to provide a means for obtaining repeatable, standard concentrations of sediment resuspended in supernatant liquid without the need for pipetting apparatus or pipetting operations.

Another object is to provide a container and cap combination in which the container has a reservoir adapted to effectively and automatically isolate the sediment from the supernatant following centrifugation and fractionation.

A further object is to provide an improved cap construction for such applications in which a transparent plate forms part of the cap to conveniently examine specimens in the associated container without the need for a separate microscope slide.

Still another object is to provide standard and reproducible volumes and concentration ratios of sediment resuspended in supernatant liquid for microscopic examination of urine.

With these and other objects in mind, reference is made to the attached drawings in which:

FIG. 1 is a wide elevational view of the sediment container and cap of this invention;

FIG. 2 is a cross-sectional view taken along the line 22 of FIG. 1;

FIG. 3 is a cross-sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a longitudinal sectional view of the container with cap removed in the process of being filled to a predetermined level with the liquid specimen to be examined;

FIG. 5 is another longitudinal sectional view of the filled container sealed with the cap and in a position simulating centrifugation about a vertical axis;

FIG. 6 is a longitudinal sectional view of the container following centrifugation with the cap and supernatant removed and the sediment together with a small amount of supernatant fluid held in the reservoir by surface tension and atmospheric pressure;

FIG. 7 is a longitudinal sectional view of the container recapped and in an upright position at which it is adapted to be shaken several times to create a uniform resuspension of sediment in the remaining supernatant for preparing a microscope slide according to one embodiment of this invention;

FIG. 8 is a longitudinal sectional view showing the resuspended sediment being transferred from the reservoir onto the slide portion of the cap by tapping the container on the cap to free the sediment from the reservoir;

FIG. 8A is a sectional view of another and somewhat preferred embodiment of cap having a lowered slide portion showing the drop of sediment compressed by a cover slip to obtain precise volume control;

FIG. 9 is a longitudinal sectional view similar to FIG. 7 with the container recapped and in an inverted position to create a uniform resuspension of sediment in the remaining supernatant fluid in accordance with another embodiment by which the sediment is examined on a conventional slide; and

FIG. 10 is a longitudinal sectional view showing the resuspended sediment being poured from the cap onto a microscope slide.

Basically, this invention contemplates a sediment container 20 and cap 21 which are adapted to be assembled as a compact unit when centrifuging and examining a liquid specimen. Although many sediment laden liquids are adapted to be handled, this invention is particularly applicable to the examination of the solid phase of urine.

The sediment container 20 is essentially a hollow tube having an upper cylindrical section 23, an intermediate downwardly and inwardly tapered section 24 and a lower reduced reservoir 25 in which the sediment is collected during centrifugation. The upper open end of the container 20 has an upwardly and outwardly extending taper 26 and possesses a substantial knife edge to facilitate pouring of the contained liquid and prevents it from running down the exterior of the tube onto the hands of the operator. The reduced nature of the reservoir 25 advantageously retains the sediment and a small amount of the supernatant liquid therein as a result of the combined effects of surface tension and atmospheric pressure when the supernatant is decanted or otherwise removed. A depending skirt 22, substantially concentrically arranged relative to the reservoir 25 and its flat base 27, enables the sediment container 20 to stand by itself on a substantially flat surface without the aid of a test tube rack or other supporting apparatus. The exterior of the cylindrical section 23 may be provided with a circumferentially extending rib 28 or conversely a groove to serve as a convenient indication of the desired amount of liquid to be placed in the container 20. Alternatively, a shoulder may be provided on the cylindrical section by a change in internal or external diameter at this location.

Reference is now made to the cap 21 which is provided with an outer substantially cylindrical skirt 30 and a substantially concentric inwardly spaced central portion 31. The skirt is formed with an annular shoulder 32 and is adapted to sealingly engage the exterior of the open end of the container 20 in snug fit with the shoulder 32 resting on the upper edge of container 20. The central portion 31 of the cap 21 is hollowed for ease of molding and includes a plateau serving as a microscope fiat slide 33 on which the sediment may be placed for examination after centrifugation. The other end of the cap 21 has a flat face 34 so that the cap may be advantageously placed on a horizontal surface whereby the slide 33 will be horizontal and in a position to receive and retain sediment for microscopic examination. The space between the skirt 30 and central portion defines an annular -well or recess 35 for deliberately receiving sediment or any overflow from the slide 33. The shoulder 36 may be employed to conveniently nest in a slide holder (not shown) to facilitate examination of the sediment under a microscope.

To further standardize quantitative examination, the present invention contemplates standardized and reproducible depths of specimen under microscopic examination While preserving concentration ratios. In accordance with one embodiment, this is accomplished by lowering the slide 33 :below the upper edge of the skirt. In FIG. 8A, this cap construction is illustrated with corresponding parts being identified with like numerals bearing an accompanying subscript a. A planar depresssion in the surface of the slide 33 may also accomplish the desired purpose. The specimen resting on the slide 33a is preferably compressed by a cover slip 37a until the slip engages with the upper edge of the skirt 30a such that excess material will fall into the annular Well 35a. Where desired to facilitate a counting procedure, the depressed slide 33a may be cross-hatched or a separate insert with cross-hatching on it may be used.

In accordance with one embodiment of a sediment examination procedure, reference is made to FIGS. 4-8. While the container 20 is in an upright position and supported on its flat base 27, the specimen of urine to be tested is poured (see FIG. 4) into the container to the prescribed level between the inscribed line 28 and the mouth of the container. In a specific successful application of this invention, this volume will be between 4.1 ml. and ml. The cap 21 is placed in position on the container 20 forming the desired sealed connection and the unit is centrifuged throwing the heavier particulate phase or sediment of the urine radially outwardly into the reservoir 25 (see FIG. 5). As represented by FIG. 6, the cap is removed while the container 20 is inverted and the supernatant poured olf. In accordance with this invention, the urine sediment remains in the reservoir 25 by the means of surface tension and atmospheric pressure together with a small, reproducible amount of supernatant, approximately .15 ml. in the stated successful application. The supernatant is, therefore, removed quickly and efficiently.

Next, the cap 21 is replaced and the capped container unit is held in an upright vertical position, shown in FIG. 7 with the thumb of one hand at the bottom of the tube and the index finger on the cap. The operator then vigorously shakes the unit several times, notably, four to six times. This mixes the sediment with remaining supernatant to produce a uniform suspension of the sediment for examination under a microscope.

The cap 21 is removed and held on a horizontal surface with one hand. While holding tube 20 at an angle above the cap (as seen in FIG. 8), the edge of the tube 20 is struck sharply against the near side of the plateau 33 in the cap 21. This will release the suspended sediment from the reservoir 25 and will deposit a drop for examination on the plateau 33. The excess will drain into the well 35. The cap may be fitted into a slide-holder (not shown) and then the drop is examined under the microscope. If desired, a cover slip may first be placed on the drop. The excess sediment flows into the overflow area 35 in the cap 21 as shown by the arrows. The sedi ment is then ready for microscopic examination.

If, after the initial examination, it is desired to stain the sediment, the cover glass should be removed from the cap 21, a drop of stain placed in the annular well 35, the container 20 inverted and reassembled to the cap 21, the assembly shaken to produce thorough mixing and the balance of the procedure repeated as above.

An alternate method of this invention is illustrated in FIGS. 9 and 10 and is adapted to be performed if the operator wishes to examine the urine on a standard microscope slide. In this connection, the capped unit is inverted for shaking, as in FIG. 9, rather than the upright position of FIG. 7. While the operator has a thumb on the cap 21 and index finger on the bottom of the container 20, the unit is shaken several times. The sediment is, accordingly, collected in the well 35 of the cap 21. The cap 21 containing the sediment is then removed from the container 20 and the sediment may be deposited one drop at a time on a conventional slide 37 for microscopic study, by gently tapping the cap against the slide as shown in FIG. 10.

Material may also be emptied from the tube directly onto the slide 37 if, after shaking, the container 20 is not inverted. In such a case, the cap 21 would first be removed and the container 20 inverted over the slide 37 and tapped against the slide.

Thus, a number of advantages of the present invention will become apparent. A low cost disposable tube and cap of suitable material is provided. The outside surface of the cap may be advantageously frosted and before centrifugation may receive patients code mark. Accordingly, there is less likelihood of mixing up specimens at the time of microscopic examination. The use of stirring rod and pipette is avoided and a microscope slide is conveniently replaced by cap 21. Although the disclosure herein has been directed particularly to sediment suspended in urine, the invention may also apply to cells suspended in blood, crystals suspended in water, metal particles suspended in oil, etc. A consistent concentration ratio from test to test is closely controlled so that realistic standards (measured in number of red cells, casts, crystals, etc., per high power microscopic field) may be applied for diagnostic purposes. The range of concentration ratios using standard procedures may vary from 15 ml./.l ml. (1 drop) 150, to 10 ml./1 ml. 10. With this invention, if the container 20 is filled to the circumferential groove (4.1 ml.), the concentration ratio Will be almost exactly 4.1 ml./.15 ml. 27. The circumferential skirt 26 at the bottom of the tube 20 permits the tube to stand on the table without the need of a test tube rack. A skirt has been selected, rather than a solid bottom, in order to facilitate injection molding. When the tube is to be used in applications that require the pouring of material from its mouth in the usual manner, it will be found that residual droplets will tend to accumulate on the interior of the rim and not on the exterior. This feature prevents contamination of the operators hands and is effected by the tapered and very thin section at the mouth of the tube.

Thus, the above mentioned objects of the invention, among others, are achieved. The range and scope of the invention are defined in the following claims.

We claim:

1. A capped sediment container for initially containing sediment laden liquid and for use with a centrifuge adapted to fractionate the liquid and separate the sediment therefrom comprising a substantially hollow sediment container having an open end and a closed end defining a reservoir of reduced dimension with respect to the remainder of the container for receiving the sediment collected during centrifugation of the liquid, said reservoir having dimensional characteristicsdependent upon the liquid being fractionated to retain a fixed volume of the liquid therein by surface tension and atmospheric pressure when said cap is removed and the container is inverted, the cap mounted on the open end and the cap and the container defining connecting means to connect the cap with the container and seal the liquid therein, the interior of the sediment container including an inwardly tapered section extending between the reservoir and the remaining part of the container interior, said container having a capacity of approximately 4-15 milliliters, and said reservoir having approximately 0.10-1 milliliter of liquid remaining with said sediment after the container is inverted and the supernatant poured off.

2. A capped sediment container for initially containing sediment laden liquid and for use with a centrifuge adapted to fractionate the liquid and separate the sediment therefrom comprising a substantially hollow sediment container having an open end and a closed end defining a reservoir of reduced dimension with respect to the remainder of the container for receiving the sediment collected during centrifugation of the liquid, said reservoir having dimensional characteristics dependent upon the liquid being fractionated to retain a fixed volume of the liquid therein by surface tension and atmospheric pressure when said cap is removed and the container is inverted, the cap mounted on the open end and the cap and the container defining connecting means to connect the cap with the container and seal the liquid therein, the cap including a central portion adapted to be disposed interiorly of the container and an outer substantially concentric skirt connected at one end to the central portion and spaced therefrom at the other end, the skirt having a shoulder on its inner face, the shoulder being adapted to rest on the upper end of the container to thereby form a seal between the container and the cap.

3. A combination is accordance with claim 2 wherein the central portion of the cap includes an inner microscopic plate portion on which a specimen of the sediment may be placed for microscopic analysis.

4. A combination in accordance with claim 2 that has the connection between the central portion and the concentric skirt defining a flat annular surface by which the capmay rest on a horizontal surface while a specimen of the sediment is being examined on the microscopic plate portion.

5. The invention in accordance with claim 2 wherein the inner face of the skirt is tapered outwardly to its free end to facilitate pouring of the specimen from the annular recess formed between the skirt and the central portion of the cap.

6. A sediment container for initially containing sediment laden liquid and for use with a centrifuge adapted to fractionate the liquid and separate the sediment therefrom having a substantially tubular body having an open end and a closed end defining a reservoir of reduced dimension with respect to the remainder of the container for collecting the sediment while centrifuging, said reservoir having dimensional characteristics dependent upon the liquid being fractionated to retain a fixed volume of the liquid therein by atmospheric pressure and surface tension when said container is inverted, the container having an annular concentric skirt at the closed end disposed about the reservoir to permit the container to stand in a vertical position, the interior surface of the sediment container at the open end being outwardly tapered to facilitate pouring of the liquid from the container, the interior of the sediment container including an inwardly tapered section extending between the reservoir and the remaining part of the container interior, said container having a capacity of approximately 4-15 milliliters, and said reservoir having approximately O.101 milliliter of liquid remaining with said sediment after the container is inverted and the supernatant poured 01f.

References Cited UNITED STATES PATENTS 3,080,964 3/1963 Robinson et al 21537 3,107,805 10/1963 Asher 23326 X 3,115,460 12/ 1963 McCormick 23292 X 3,170,838 2/1965 Archer.

3,190,731 6/ 1965 Weiskopf 23292 JOSEPH SCOVRONEK, Primary Examiner U.S. Cl. X.R. 

